Release kinetics and up-take studies of model fluoroquinolones from carbomer hydrogels

A Ciprofloxacin Extended Release Tablet Based on Swellable Drug Polyelectrolyte Matrices

“…5 and 6). It has been previously reported (8) that the introduction of Na cation as third component of CB-Cip complexes increases their water affinity. Therefore, in order to improve the swelling properties of the complexes, increasing proportions of Na + were introduced as a third component.…”

“…1), based on CB-Cip complexes. This antimicrobial fluoroquinolone was selected because the properties of hydrogels of CB-Cip were previously evaluated (8). In such hydrogels, a high degree of counterionic condensation is generated by the acid base reaction between the carboxylic groups of CB and the aliphatic piperazine nitrogen of Cip.…”

Ophthalmic controlled release in situ gelling systems for ciprofloxacin based on polymeric carriers

“…For the formulations under investigation, the release exponents (n) were close to 1, suggesting that ciprofloxacin was delivered from gels by zero order kinetics. Similarly, Vilches et al (2002) reported zero-order kinetics for the release of ciprofloxacin from carbomer hydrogels. The slight deviation of the n-value that was observed in some cases could be attributed to the swelling properties of these formulations following the ingress of water.…”

“…The dissociation of ionic pairs has contributed in facilitating the drug release from gel matrices. Vilches et al (2002) reported that ionic pairing between fluoroquinolones and carbopol is the main interaction that determines the enhanced aqueous compatibility and releasing properties of the drug. Moreover, loading carbopol with fluoroquinolone together with an appropriate amount Na + yields physically stable dispersion that behaves as a molecular matrix of fluoroquinolones, able to deliver the drug at a constant rate (zero order) in contact with a biological fluid-like solution.…”

“…The solubility of ciprofloxacin is pH-dependant and is ranging from 6.19 mg/ml at pH 5 to 0.15 mg/ml at pH 7 and 37°C. The low aqueous solubility of this compound at pH close to 7 is due to that in aqueous solution, ciprofloxacin exists in its zwitterionic form due to the acid/base interaction between the basic nitrogen of the piperazine and the carboxylic acid groups (Vilches et al, 2002). This interaction is the main reason that prevents the design of liquid dosage forms such as ophthalmic and parenteral solution, because the aqueous compatibility of these drugs occurs at rather basic or acidic pH (Allemandi et al, 1999).…”